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Патент USA US3091728

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May 28, 1963
Filed July 8, 1960
te States atent C)
ice l
Patented May 28, 1963
introductory and exhaust system leads to corrosion prob
lems. The possibility of physical blocking of the intro
ductory and exhaust systems by solid iodine is an addi
3,091 718
Joel Shurgan, Brooklyn, N .Y., assigner to Duro-Test Cor
Ièoraktion, North Bergen, NJ., a corporation of New
tional problem.
The present invention relates to the manufacture of
a lamp which has all the advantages of the iodine cycle
without using molecular iodine, which interferes with the
Filed July 8, 1960, Ser. No. 41,621`
3 Claims. (Cl. 313-222)
normal manufacturing cycle. In accordance with this
invention, a gaseous halogen or halogen compound (gas
eous scavenger) is introduced into the system by itself
This invention relates to the manufacture of lamps and
more particularly to a lamp to which a gaseous scavenger
or in combination with a carrier gas and/ or the lamp fill
is added for the purposes of preventing the blackening of
the lamp wall, increasing filament life, and for maiu
taining a substantially constant lumen output during the
life of the lamp.
In the past, incandescent lamps having tungsten fila 15
ments have been manufactured which utilize elemental
iodine in an iodine cycle to remove evaporated tungsten
from the wall of the bulb. The iodine cycle serves the
gas. By using a gaseous halogen or halogen compound
it is possible to realize all the advantages of the iodine
cycle. In addition, the lamp may be manufactured with
a readily controlled and measured concentration of halo
gen or halogen compound, Without heating the walls of
the introductory system and carefully controlling this
temperature. The manufacture of the lam-p of the pres
ent invention may be carried out by conventional lamp
purpose of preventing wall blackening, caused by the
evaporation of the tungsten filament by redepositing the 20 manufacturing machinery and processes. The manu
facturing processes may also be carried out in one opera
evaporated tungsten on the filament.
tion, if the lamp fill gas is mixed with, or contains the
In the iodine cycle type of lamp referred to above a
gaseous halogen or halogen compound. Furthermore,
small quantity 4of molecular iodine (I2) in so-lid form is
there is no possibility of blocking the introductory and
introduced into the lam-p during the process of manu
facture. During the operation of the lamp, tungsten is 25 exhaust systems, since elemental iodine is not used.
Also, the corrosion problem is substantially reduced in
transferred from the filament to the lamp wall by normal
comparison with the use of solid iodine, since the con
evaporation and diffusion, or by the water cycle. The
centration of gaseous halogen or halogen compound at
molecular iodine (I2) which is introduced into the lamp
the walls is much less than for solid iodine.
during the process of manufacture is changed into iodine
It is therefore an object of this invention to produce a
atoms (I) by the pyrolysis of the molecular iodine in the 30
lamp which has a substantially constant lumen output
vicinity of the filament. The iodine atoms diffuse to the
during its life.
lamp wall and under the proper conditions react with the
Another object of this invention is to produce a lamp
adsorbed tungsten (W) forming volatile tungsten iodide
having a constant lumen output wherein the blackening
(WI2) which diffuses to the filament. The tungsten
iodide (W12) is then decomposed at the filament by the 35 of the lamp Wall is prevented by a gaseous scavenger.
Yet a further object of this invention is to provide a
heat of the filament resulting in the redepositing of
process for introducing a halogen scavenger into the
tungsten on the filament and the production of iodine
lamp to prevent blackening, the halogen scavenger being
atoms which then diffuse to the lamp Wall to repeat the
The iodine cycle in the above type of lamp depends on
the reaction
Still another object of this `invention is toprovide a
lamp into which a gaseous halogen compound is intro
duced in order to prevent blackening.
Other objects and advantages of the present invention
where the forward reaction predominat-es at the lamp
Will become more apparent upon reference to the follow
wall and the reverse reaction at the filament. A small 45 ing specification and annexed drawing in which:
amo-unt of tungsten iodide is also formed in the gas phase
FIGURE 1A shows a plan View of an incandescent
due to a reaction between tungsten in the diffused form
lamp; and
W(g) and iodine atoms (I) or molecular iodine (I2)
FIGURE 1B shows the lamp of FIGURE 1A rotated
with a molecule of the inert lamp fill gas removing the
by 90 degrees.
excess energy. The gaseous tungsten iodide also serves 50
IReferring now to FIGURES lA and 1B, one type of
the aforementioned purpose.
In general, lamps using an iodine cycle show a high
lumen maintenance; i.e. the lumen output of the lamp
remains substantially constant throughout the life thereof
incandescent lamp with which the present invention may
be utilized, is shown. This lamp is of the `type which
has a `tubular envelope 11 which is made of a suitable
vitreous material such as quartz, and which is preferably
and does not decrease with filament age.
A tungsten filament 13, which is shown as being
manufacturing and engineering difñculties are encountered
of the coiled type, is supported within the envelope 11 by
in producing this type of lam-p. One such difficulty in*
-two supports 1S. The supports 15 are also formed of a
volves the introduction of controlled amounts of molecular
suitable heat resistant material, such as tungsten, and
iodine into the lamp. When molecular iodine is used _it
are preferably :spiral in shape. The supports 15 hold the
deposits along the introductory system in amounts de~ 60 filament 11 at the innermost turn of the spiral and the
pendent on the wall temperature at the point of deposition.
outer turn of the spiral presses against the inside of the
The amount of iodine actually introduced into the lamp
>envelope 11, thereby supporting the filament 13 Within
will be dependent on the vapor pressure of iodine at the
the envelope.
temperature used. Thus, to control the amount of iodine
The coiled filament 13 terminates at each end thereof
introduced, the temperature of the introductory system 65 in a solid wire 17 by means of which current is supplied
walls and lamp must be carefully controlled. Further
to the filament 13. Each of the wires 17 is preferably
-a solid piece of tungsten. A lead-in connector 19 is con
more, the iodine must be introduced into an evacuated
nected to each of the lead-in Wires 17 -by suitable process
lamp, before the addition of fill gas, for otherwise the
However, many 55 clear.
thermal diffusion time required for the thorough mixing
such as welding, etc.
The lead-in connectors 19 are
of the fill gas and iodine vapor becomes uneconomic for 70 preferably of a flattened out shape, as shown, and may
be formed with the edges thereof tapered or feathered,
manufacturing purposes. In addition, the intimate con
as is well known in the art. The lead-in connectors 19
tact between molecular solid iodine and the walls of the
are also formed of a suitahle material such as molyb
all of the advantages of the iodine cycle are obtained.
During operation «of the lamp, when a gaseous halide
is used as the scavenger, the gaseous halide is partially
decomposed by thermal energy at the filament into hydro
denum, etc. The lead-in connectors 19 are shaped at
the end opposite the lead-in wire 17 with a lead-in Wire
21 which extends out through the envelope 11 and to
which the terminals of the current source for the lamp
gen and the corresponding halogen v(brornine, chlorine
or iodine). The evaporated tungsten combines at the
filament 13 are connected.
In order to secure the filament structure Within the
envelope 11 and to form a vacuum seal for the lamp, the
end of the tungsten Wire 17, the connector 19 and part
of the lead-in 21 are sealed into the end of the envelope 10
by a pressing operation. The ends of the tubular lamp
envelope are therefore narrowed down and a vacuum seal
is provided.
A tubulation 23 is provided through which the lamp
is first exhausted and then filled with the fill gas and the
gaseous halogen or halogen compound scavenger. After
lamp Wall to form tungsten halide which is volatile at
the ‘operating temperature of the lamp wal‘l. From this
point on, a conventional type iodine cycle occurs in which
the tungsten halide evaporates from the bulb wall and
is decomposed at the filament by thermal energy. The
tungsten is then redeposited on the filament and the halo
gen is regenerated into the system.
It should be noted that once iodine or other halogen
is formed at the lamp filament by the decomposition of
the gaseous halogen compound scavenger it may enter
into one or both of the following reactions:
the filling operation is completed, the tubulation 23 is
tipped off to provide a complete vacuum seal for the
In the lamps previously described wherein solid molec 20
ular iodine is introduced into the lamp, the iodine de
where H is hydrogen and X represents the halogen. The
posits on the inside wall of the lamp and also on the tub
reformed halide is then `decomposed by thermal energy
ing and other parts of the system used for exhausting and
from the filament into the elemental halogen, restarting
filling the lamps. This interferes with the evacuation of
the cycle over again.
the lamp and also causes corrosion problems in the ex
haust system.
In accordance with the present invention and to over
come the manufacturing problems and disadvantages of
the lamp using molecular iodine, a gaseous halogen or
halogen compound is introduced into the lamp through
the tubulation 23 after the lamp has been evacuated.
This may be accomplished lin a number of ways. The
gaseous scavenger may be mixed with the fill gas prior
When the lamp envelope is made of quartz, the hydro
gen formed in the decomposition of the gaseous halide
may diffuse through the quartz bulb wall leaving free
elemental halogen in the lamp to operate in a conven
tional iodine type cycle. It should be noted however
that even when some hydrogen remains in the lamp, that
the advantages of the iodine type cycle are still retained
while the ditiiculties encountered in introducing a scav
enger in molecular form into the lamp are overcome.
to the introduction of the mixture into the lamp or else
When bromine vapor or chlorine gas in a carrier gas
the fill gas and the scavenger may be introduced into the 35 mixture is utilized as the scavenger, it operates in the
lamp separately. The gaseous halogen or halogen com
pound rnay also first be mixed with a small quantity of
inert gas, called a carrier gas, and then the pre-mixture
may be further mixed with the fill gas prior to introduc
manner previously described with respect to the molecu
lar iodine. However, it should again be realized that
since the vscavengers are of gaseous form, the difficulties
in introducing the molecular halogen directly into the
tion of the composite mixture into the lamp. The pre 40 lamp
are not encountered.
mixture and the fill `gas may also be introduced into the
lamp separately.
With respect to the fill gas .and carrier gas usuable
with the invention, :any inert gas such -as argon, other
When bromine or chlorine are utilized as the scavenger,
either in the form of bromine vapor or gaseous chlorine
or in the form of hydrogen bromide or hydrogen chlo
rare gas, nitrogen, or any gas not precluded by conven
ride, the operating temperature 4of the lamp bulb must
halides, such as hydrogen bromide, hydrogen chloride
»and hydrogen iodide. Other gaseous halogens which
increasing power input, modifying the geometry of the
lamp bulb, etc.
4of the invention, the halogen compound hydrogen iodide
is utilized.
When using gaseous halides such as hydrogen bromide,
hydrogen chloride and hydrogen iodide, the halides are 55
lumen maintenance is accomplished by the introduction
example: lamps having glass envelopes or envelopes of
tional lamp manufacture may be utilized.
45 be made higher in order to effect the desired cycle. This
does not pose any problems since the temperature may
Suitable gaseous halogen compound scavengers which
increased by any of several techniques, for example,
may be utilized with the present invention include gaseous
Therefore it has been seen that a novel lamp has been
may be utilized are bromine Vapor in a carrier gas and 50
described Which has a high lumen maintenance. The 4high
chlorine in a carrier gas. In a preferred embodiment
of a gaseous scavenger, in the form -of a gaseous halogen
or a gaseous halogen compound into the lamp, along with
or separately from the lamp fill gas. This procedure Over
comes the disadvantages encountered when elemental io
preferably mixed with the fill gas before the introduction
dine or other halogen in molecular form is introduced
of the mixture into the lamp. The gaseous halide and
in the system.
the fill gas may also be introduced into the lamp sepa
While the invention has been described With respect to
rately. lf desired, the gaseous halide may first be mixed
with the carrier `gas to form la pre-mixture and then the 60 a conventional type of tubular, coiled filament quartz
pre-mixture may be introduced into the lamp as part of a
lamp, it should be realized that it is not limited thereto
since it may also be used with other types of lamps, for
composite mixture of fill gas, or separately from the fill
When bromine vapor or chlorine gas is used, it is pref
other vitreous material; lamps of »different envelope
erably first mixed with la quantity of a carrier gas. The 65 shapes and geometries; lamps utilizing straight or coiled
filaments in different configuration; etc.
pre-mixture may then be mixed with the fill gas before
introduction into the lamp or the pre-mixture and the
Although a particular structure has been described, it
fill gas may be separately introduced into the lamp.
should be understood that the scope of the invention
The amount of gaseous scavenger introduced should
should not be considered to be limited by the particular
be such as to maintain a partial pressure in the lamp in 70 embodiment of the invention shown by way of illustra
the range between 1.0 mm. and 40.0 mm. of mercury
tion, but rather by the appended claims.
pressure and including the extremes thereof. yIn a pre
What is claimed is:
ferred form of the invention a partial pressure of `about
l. In a lamp comprising a metallic filament within an
8.0 mm. is maintained.
envelope, a gaseous compound Within said envelope
With a vgaseous scavenger introduced into the lamp 75 selected yfrom the group consisting of hydrogen chloride,
formed of a ‘material containing silica which has sub
stantially the same or greater permeability to hydrogen
as fused silica, thereby the hydrogen is able to diiîuse
out through said envelope upon disassociation from said
gaseous compound.
2. An improved lumen maintenance lamp comprising
a metallic lamp iilament sealed Within a substantially
air-tight envelope of vitreous glass material which has
substantially the same permeability to hydrogen as fused 10
silica material, `said ’filament having leads connected there
to which are adapted to be connected to a -source of
power for heating said ñlament, said envelope containing
a quantity o-f a gaseous compound selected from the
group consisting `of hydrogen iodide, hydrogen chloride
and hydrogen bromide, said -envelope being permeable
to hydrogen whereby the hydrogen is able to diíîuse out
through said envelope upon disassociation `from said gase
ous compound.
3. In a lamp comprising a metallic filament within
an envelope, a halogen compound within said envelope,
said compound containing a halogen scavenger which
is to be retained in said envelope and an element which
is to be expelled from said envelope, said envelope formed
of a material which is relatively highly permeable to said
unwanted element and relatively impermeable to said
halogen scavenger whereby said unwanted element diffuses
out through said envelope upon disassociation from said
hydrogen bromide and hydrogen iodide, said envelope
References Cited in the file of this patent
Wolff et al. __________ __ Ian. 10, 1928
Van Liempt __________ __ Sept. 5, 1933
Fridrich et a'l _________ __ Apr. 21, 1959
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